Mechanical Energy

Mechanical Energy is energy due to position or motion. Position: This means that matter can have energy even though it is not moving. If you knock something off of your kitchen counter, it falls to floor and a change has occurred. Energy is required to cause a change. Without the energy, the object would have never fallen or changed. So where did this energy come from if the object was not moving? This type of energy is energy due to position ‰ An object has energy due to its position above the ground. The higher an object is from the ground, more energy it has. Motion Things that move can cause change. When a series of dominos is set up and set in motion, the first domino hits the second and causes it to move. The energy in the motion of the first domino causes the second domino to change and so on. Since energy is required to cause a change, energy must be present. The type of energy in the dominoes example is energy due to motion ‰ An object in motion has energy. The faster something is moving, the more energy it has

Demonstration: 1. Mold the clay until you have a surface that is approximately 1 cm thick, it can be in any design you wish 2. Drop the marble from various heights while trying to hit your design 3. Compare the dents created in the clay when dropped from the different heights Explanation: The mechanical energy of the marble depends on how high it is located from the floor. The higher the marble is the more mechanical energy it has. When you release the marble, the energy of position is changed, or converted, into energy of motion. The energy of motion then causes a change (that’s what energy does!) in the clay that it hits. So the higher the marble was dropped from, the more mechanical energy it had and the greater the change – the dent in the clay (assuming you hit your target).

Thermal Energy

Low Temperature

High Temperature

Thermal (heat) energy is energy from the motion of particles that make up an object All objects are made up of stuff. That stuff is known as atoms and molecules. Those molecules are ALWAYS moving. The faster the particles move, the hotter the object gets.

Demonstration: 1. Put on some safety goggles 2. Plug in the hot plate and turn it on to a temperature setting of 10. DO NOT TOUCH THE HOT PLATE ONCE IT IS TURNED ON! 3. Fill the beaker half full of water and place it on the hot plate 4. Put the balloon around the rim of the test tube 5. Once the beaker of water starts to bubble, place the test tube in the water 6. Observe the balloon as the temperature increases 7. Remove the test tube from the hot water using the test tube holder, observe what happens to the balloon 8. Turn off the hot plate and leave it for the next group Explanation: The heat from the beaker causes the air molecules in the test tube to move faster. When they move faster, they move into the balloon and press against the sides of the balloon. This pushing causes the balloon to inflate or get bigger. When you remove the test tube from the water, it cools down. As it cools down, the balloon starts to deflate, or get smaller. A hot air balloon works the same way. On the balloon there is a flame that shoots fire into the balloon. The fire causes the air molecules to move faster and inflate the balloon, which causes it to move (rise). When they want to go down, they lower the flame.

Electromagnetic Energy

Electromagnetic (light) energy is energy that is carried by waves. Examples of energy carried by waves are light, microwaves, X-rays, and radio waves. When those types of waves move, they carry energy with them. When they hit something they cause things to change. Any time a change takes place, energy must be present. For example, light and microwaves can cause things to heat up and radio waves cause things to vibrate and create sound. Have you ever tried to burn ants with a magnifying glass? When you do, the light waves from the sun travel through the air. The waves are carrying energy with them. Luckily, the light waves are spaced out enough that the earth’s surface does not get that hot. When you use your magnifying glass, you are pulling a lot of waves together and concentrating them on one surface. As the waves hit the ant, they cause it to change. This change is the ant getting hotter. You can also prove that light is energy to yourself by setting out something black and something white in the sun. When you check on the items later, you will find that the black object got hotter. This is change, how did it happen? Nothing was around except the sunlight! Therefore, the light must have caused the change so it must be energy

Demonstration: Follow the directions on the separate sheet to make to see if you can make the speaker work Explanation: A speaker is a device that converts, or changes, electrical energy into sound energy. When electricity comes into the speaker, it causes the diaphragm (usually just a piece of black paper) to vibrate. Those vibrations are known as sound waves. The sound waves then travel through the air until they hit your ears. When they do you hear a change. Remember that energy is responsible for changes so sound must be energy.

Electrical Energy

Electrical energy is energy created from the moving of electrons All matter is made of stuff. That stuff is known as atoms. One of the components of an atom is known as an electron (they are the smaller circles in the picture above). In certain matter, those electrons move freely. These types of matter are known as conductors (examples: wire, silverware, you). The movement of the electrons causes the object to change. Although this sounds complicated, all you need to remember is that the movement of special particles in matter produces electricity and this electricity can only travel in special types of materials known as conductor. As you are well aware, electricity is used to cause a lot of changes. Those changes include operating a pencil sharpener, a lamp, a computer, a radio, and much, much more.

Demonstration: Use the materials at your table to try and make the light bulb light up. Be careful Explanation: In this lab, you created a circuit. The circuit is made of metal wires, which is a conductor, so the electrons can move. The electrons are pushed through the wires by the battery. In a circuit there must be a continuos flow of electrons through the wires from the battery, to the object you are supplying energy to, and back to the battery in order for them to work. As soon as there is a break, the circuit no longer works. Switches are purposely put in circuits so that we can control them. Switches purposely create a break in the circuit so that you can shut it down. If you did not have switches then radios would never turn off! Since this lab did not have a switch, the light stays lit up as long as the circuit is held together. When the electrons travel through the light bulb, they cause a special piece of metal in the light bulb to get so hot that it glows. That glowing is the light that we see.

Chemical Energy Molecules Chemical bonds

Chemical energy is energy created when chemical bonds are created or destroyed All matter is made of stuff. That stuff is known as atoms or molecules. Atoms and molecules are held together by bonds (much like a REALLY, REALLY strong glue). When those bonds are broken or created, they produce energy. Earlier this year we looked at glow sticks. When you break the glow stick, the two liquids in the stick are free to interact. When they do, their chemical bonds are broken and then reconnected to form a new liquid. The energy released from the chemical bonds cause a change that produces a glowing light.

Demonstration: Enjoy the food at your table! Explanation: Food that you eat has chemical bonds. When you eat the food, your body breaks down the chemical bonds and releases energy. That energy is used by you to complete your daily functions such as running or studying science!